The objectives of this study are to define: a) dose-dependent glucose lowering efficacy of CP-368,296 over a period of three months, as indicated by HbA1c and fasting serum glucose concentrations, b) dose-dependent efficacy of CP-368,296 on correlated metabolic outcomes, including mixed meal tolerance and serum lipids, c) dose-dependent safety issues. In addition to routine safety monitoring, one objective of this study is to specifically examine dose-dependent inhibition of skeletal muscle glycogen phosphorylase.